139results about How to "Suppresses higher harmonics" patented technology

The invention discloses an AC electrified railway traction in-phase power supply device based on a YNd11 connection transformer, the traction transformer of the device is a three-phase transformer (T1) connected in YNd11, and the three primary sides of the transformer (T1) in a YN connection The three phases A, B, and C are connected to the high-voltage public power grid, and the low-voltage side terminals (a, b, c) of the transformer are connected to a power flow controller (IC), and the terminals a and b are connected to the electrified railway catenary (TR) . The device can realize the same-phase power supply for the entire railway line without phase separation, and the power supply voltage is stable, ensuring the high-speed and heavy-load operation of the locomotive; at the same time, the device can eliminate the negative sequence, reactive power and harmonics of the railway traction load on the electric energy of the public grid impact, low cost, and easy implementation.

The invention discloses a brushless doubly-fed motor of a wound rotor, pertaining to the technical field of motors. In an AC (alternating current) brushless doubly-fed motor of the invention, two sets of three-phase windings with respective numbers of pole pairs as P1 and p2 are arranged on a stator; a rotor adopts a multi-phase winding and a phase number m meets the relational expression: m= (P1 + p2) / mk, wherein, when P1+ p2 is an odd number, mk is equal to 1; when P1 + p2 is an even number, and mk is equal to 2 and rotor slots are uniformly distributed along the circumference of an air gap. Number of rotor slots Z' meets the relational expression: Z'=n (P1 + p2), wherein, n is a positive number; coils of rotor winding are multi-turn structures; the coil number of each phase winding is nmk; the span of each coil is equal but the specific value of turn number between the coils is different; and when the number of coils of the phase windings is less than or equal to nmk, all coils in phase windings are coupled when in short circuit after being series-connected. The brushless doubly-fed motor has the advantages that the span of winding coil can be flexibly changed and the turn number of each coil can be different, thereby realizing the purpose of maximally reducing the higher harmonic.

The invention discloses an output current wave shape control method for a triphase Active Power Filter (APF). A T-shaped filter and a current wave shape controller are adopted to control the output current wave shape of the triphase AFT. The output filter for each phrase bridge arm of an inverter is a capacity connected to the middle point of two inductances connected with each other in series, and form a T-shaped structure, namely T-shaped filter; the calculation method for wave shape controlling is conducting Alfa, Beta, Omicron transformations to instruction current of the triphase APF, actual output current and the voltage of the power network, so as to realize decoupling of the wave shape controlling of the abc triphase output current; and respectively conducting pole assignment to the single-phrase system under decoupled Alfa, Beta, Omicron axis system, and correcting the error between the APF actual output current an the instruction current, so as to get instruction voltage of each phrase under the alfa, beta, Omicron axis system; and at last sending the instruction voltage to a space vector modulating module, so as to confirm the on-off signal of each bridge arm switch tube, thereby causing the actual output current of the PFA to accurately track the instruction current.

The invention discloses a wide-stopband LTCC (low temperature co-fired ceramic) band-pass filter based on a magnetoelectric coupling counteraction technology. The wide-stopband LTCC band-pass filter based on the magnetoelectric coupling counteraction technology comprises two quarter-wave resonators, a metal floor and a pair of feed structures, wherein the resonators and feed patches are distributed on four conductor layers; the first layer is a feed layer with large feed patches and CPW (coplanar waveguide) feed ports; the two quarter-wave resonators are distributed at the second layer and the fourth layer, and the third layer is a grounding layer; the feed patches transmit energy to the resonators by means of broadside coupling; the resonators transmit energy to each other via side coupling, magnetic coupling and electric coupling exist between the two resonators simultaneously, the coupling in intervals close to a grounding end mainly is the magnetic coupling, and the coupling in intervals close to the open-circuit ends of the resonators mainly is the electric coupling; and the position of the transmission zero point of the filter can be conveniently adjusted by adjusting the intensities of the magnetic coupling and the electric coupling. The wide-stopband LTCC band-pass filter based on the magnetoelectric coupling counteraction technology disclosed by the invention is provided with a plurality of transmission zero points, as well as is excellent in selectivity and stopband suppression performance, and compact in structure.

The invention discloses a dual-frequency receiving antenna and a dual-frequency rectifying antenna. The dual-frequency receiving antenna and the dual-frequency rectifying antenna are used for solving the problems that an existing dual-frequency receiving antenna is large in size and small in gain, an existing dual-frequency rectifying antenna is large in size, can not receive weak energy and is not suitable for remote transmission, and a rectifying circuit is poor in reliability. The dual-frequency receiving antenna comprises a rectangular radiating patch. A Z-type groove used for achieving dual-frequency characteristics is formed in the radiation patch. The lower end of the radiation patch is sequentially connected with a dielectric substrate layer and a metal earth plate through a coaxial line. The coaxial line is in circuit connection with the rear end of the radiation patch. An air dielectric layer is formed between the radiation patch and the dielectric substrate layer. The portions, arranged between the radiation patch and the dielectric substrate layer, outside the coaxial line are provided with metal sheets in a bilaterally-symmetric mode. The upper ends of the metal sheets are connected with the radiation patch. The lower ends of the metal sheets are connected with the dielectric substrate layer. One end face of the radiation patch is further connected with the metal sheets connected with the dielectric substrate layer. The dual-frequency receiving antenna and the dual-frequency rectifying antenna can be widely applied in the fields of communication, medical treatment, industry and the like, for microwave power transmission.

The invention discloses a high-order harmonic suppression circuit for a radio frequency power amplifier. The circuit comprises a transistor, a high-order harmonic suppression circuit, a fundamental wave matching circuit and a direct current bias circuit, wherein the high-order harmonic suppression circuit is positioned between the transistor and the fundamental wave matching circuit; the fundamental wave matching circuit and the direct current bias circuit are positioned between the high-order harmonic suppression circuit and a load. The high-order harmonic suppression circuit is implemented by a low-pass filter or a band-pass filter, the fundamental wave frequency of the radio frequency power amplifier is within the pass band of the low-pass filter or the band-pass filter, and all harmonic frequency components are within the stop band of the filter; meanwhile, low insertion loss exists in the low-pass filter or the band-pass filter, and high insertion loss exists in the stop band. According to the high-order harmonic suppression circuit, a high-order harmonic suppression function of the power amplifier is enhanced, and the linearity, efficiency and output power of the power amplifier can be improved.

The invention discloses a design of a reflective wave strip sheet with a single-stage diffraction characteristic and a manufacturing method thereof. The reflective wave strip sheet comprises a transparent substrate; and multiple high-reflectivity circular elements which are formed on the aforementioned transparent substrate. The aforementioned circular elements are randomly distributed in elliptical rings of the reflective wave strip sheet and are not intersected. Radiuses of the circular elements change along with size of width of the elliptical rings. The range of the radiuses of the elements arranged between the (n-1)th and nth (n is an integer greater than 1) rings is [rnmax, rnmin], wherein rnmax=(an-an-1) / 2, rnmin=(bn-bn-1) / 2, an in the formula is the long axis of the nth ring line, and bn is the short axis of the nth ring line. The reflective wave strip sheet only has zero-order and positive and negative one-order diffraction so that high-order diffraction can be effectively inhibited and harmonic pollution can be eliminated. Meanwhile, the reflective wave strip sheet has a binary structure characteristic so that the reflective wave strip sheet is easy to manufacture and realize. The reflective wave strip sheet with the single-stage diffraction characteristic has characteristics of integrating dispersion, focusing and higher harmonic inhibition so that the reflective wave strip sheet can act as an optical element for leading edge science, such as soft X-ray light source focusing, monochromatization and spectral analysis.

The invention provides a converter controllable in regenerative running mode, which is a power converting apparatus capable of suppressing harmonics without increasing the size of a reactor, and reducing power loss and electromagnetic noise. A power converter (7) is configured by directly connecting AC sides of single-phase sub-converters (3) having a DC voltage lower than a DC voltage of a 3-phase main converter (2) to AC input lines of individual phases thereof in series. The main converter (2) is driven by one gate pulse per half recurring cycle and a voltage produced by each sub-converter (3) at AC terminals thereof is controlled to match a difference between an AC power supply voltage and a voltage produced by the main converter (2) at AC terminals thereof, whereby phase voltages of the power converter (7) are generated as the sums of phase voltages of the individual converters (2), (3).

The invention discloses an out-of-focus projection three-dimensional measurement method of color binary fringes. The method involves three key parts including the color binary fringe coding principle, an out-of-focus projection system and the three-dimensional measurement principle. The out-of-focus projection three-dimensional measurement method of color binary fringes has the advantages that first, according to a traditional color sine fringe projection method, the color sine fringe gray level of projection of a traditional method projector is distributed between 0 and 255, the projection speed is limited within 120 frames / s, and the measurement speed is restricted; according to the method, because the projection color binary fringes only have the two gray levels of 0 and 255, the projection speed of a projector is greatly increased, and thus three-dimensional measurement speed is greatly increased; second, the three-step phase shift method is adopted, three-dimensional measurement can be achieved with only one set of color binary fringes, and the method has high three-dimensional measurement speed; third, the method has very high practical value in high-speed and high-precision three-dimensional measurement.

The invention provides a power supply unit wherein the conduction angle of input current is widened through simple control and thereby the power factor is improved and the harmonic component of the input current is reduced. The power supply unit is provided with a rectification circuit that rectifies the voltage of alternating-current power supply, a reactor connected with the rectification circuit, a power-factor improvement circuit that includes a plurality of switching elements and capacitor circuits and is fed as input with the output voltage of the rectification circuit, a change-over switch portion that is connected between the rectification circuit and the power-factor improvement circuit and switches the state of conduction of a current path formed between them from the state in conduction to the state out of conduction and vice versa, a change- over switch control portion that controls the state of conduction of the change-over switch portion, a pulse signal control portion that generates and outputs pulse signals for turning on and off the individual switching elements in the power-factor improvement circuit, and a switch driving portion that receives the pulse signals from the pulse signal control portion and drives the switching elements in the power-factor improvement circuit.

The invention discloses an LTCC (low temperature co-fired ceramic) wide-stop band band-pass filter. The filter comprises three 1 / 4-wavelength short-circuit stepped-impedance resonator with different shapes on different layers, wherein the three resonators are staggered in an LTCC substrate and formed by combining short-circuit stepped-impedance resonators loaded on adjacent layers with capacitor chips respectively; and the three resonators have the same fundamental frequency and different secondary harmonics and higher harmonic frequencies. Through the invention, the structural characteristics of LTCC are made full use in the arrangement of the resonators so that the three resonators are positioned on different circuit layers respectively, staggered distribution is realized, and the circuit volume is reduced; moreover, the 1 / 4-wavelength resonators have the same fundamental frequency and different shapes and higher harmonic frequencies, the parasitic passband of the filter is effectively suppressed, and the stop band property of the filter is improved. The invention is suitable for the microwave filtering circuits.

The invention provides a broad-stopband electrically-tunable dual-frequency band-pass filter comprising a metal microstrip line in the front, a dielectric board layer, a first input / output port, a second input / output port, ground metal vias and a metal coating arranged on the back of the dielectric board layer. The metal microstrip line in the front is composed of a uniform impedance resonator, a short-circuited stub and an input / output coupling line; a variable capacitance diode is loaded between the uniform impedance resonator and the short-circuit stub, forming a tunable structure; the tail end of the short-circuited stub is grounded through the ground metal vias. The broad-stopband electrically-tunable dual-frequency band-pass filter is compact in structure, allows dual-frequency tunable, is low in band-pass internal insertion loss and good in out-of-band rejection and has broad stopband.

The invention discloses a 28GHz radio frequency power amplification circuit applied to a fifth-generation communication millimeter wave frequency band. The circuit comprises an input matching circuit,an interstage buffer circuit, a final-stage power output stage, an interstage matching circuit and an output harmonic suppression matching network. Input matching adopts a T-shaped matching structure, an input stage adopts a common-source amplifier structure and is statically biased in an A-class working state, an intermediate buffer stage and a final-stage power pushing stage are statically biased in a B-class working state, the efficiency is improved, and an output matching network adopts a harmonic suppression network structure. And the harmonic suppression network adopts a series resonance structure to enable second harmonic, third harmonic and fifth harmonic to be in short circuit to the ground, so that the efficiency is improved, and the linearity of radio frequency signal output ishigher. A radio frequency input signal is subjected to power amplification through first three stages of PA, passes through a second harmonic suppression network, a broadband matching network, a third harmonic suppression network and a fifth harmonic suppression network, and finally is transmitted to a load through a coupling capacitor.

The invention discloses a digital and analog mixed simulation system suitable for a direct-current power grid. The system comprises a digital side interface and a physical side interface, wherein the digital side interface is used for receiving a first signal from an A / D so that a digital simulation subsystem carries out digital simulation according to the first signal; the digital side interface outputs a second signal to a D / A; the D / A converts the second signal into a corresponding third signal and outputs the third signal to a control system; the control system receives the third signal and a fourth signal from a measuring unit, and carries out operation of tracking control according to the third signal and the fourth signal to generate a fifth signal; and the physical side interface is used for outputting direct-current power quantity according to the fifth signal so that a physical simulation subsystem carries out physical analog simulation according to the direct-current power quantity. According to an embodiment of the invention, the digital and analog mixed simulation system is suitable for digital and analog mixed real-time simulation of a direct-current power system.

The invention relates to a magnetic integrated double inductor, which comprises two groups of coils and a magnetic core, wherein the magnetic core comprises two arms which are formed integrally and are used for the coils and at least one shared arm; a group of coils is wound on each arm for the coils; the shared arm and each arm for the coils form a magnetic flux ring; and an air gap is reserved on each arm for the coils, and the sectional area of a magnetic material for forming the air gaps is changed linearly along the arms for the coils.

The invention relates to an asymmetric DGS (Defected Ground Structure) structure cascaded filter, belonging to the field of microwave devices. A T-shaped defected grounding structure asymmetric to a microstrip line is etched on a rectangular dielectric slab as an asymmetric T-shaped DGS structure of a single unit, and the asymmetric T-shaped DGS structures of two or three single units are cascaded in parallel to form the filter. Compared with the traditional dumbbell and T-shaped DGS structures, the asymmetric DGS structure filter can effectively inhibit secondary harmonic waves and third harmonic waves of the microwave devices in a specific frequency range, and the volume of the filter is not increased greatly. Multiple symmetric and asymmetric DGSs can be cascaded, and the cascaded product can obtain higher inhibition action on wide stopband of secondary harmonic waves and third harmonic waves of the microwave devices.

The utility model relates to an A.C. co-phase traction supply device of railway locomotive based on YN, vd wiring transformer; wherein, the traction transformer is a three-phase to two-phase balancing transformer (T), the wiring method of which is YN, vd. A rectifying inverter (Z) is connected between two outputs (b', c') of the line voltage of the transformer (T) and two outputs (a, x) of the phase voltage of the transformer (T), and the outputs (b', c') of the line voltage and the outputs (a, x) of the phase voltage are the supply ends (V1, V2) of the traction locomotive. Meanwhile, a control device of the rectifying inverter (Z) is connected with the two supply ends (V1, V2) of the traction locomotive. The utility model has the advantages of achieving the co-phase power supply in the whole line of the railway without dividing phases, being stable voltage in each section of the traction transforming station, ensuring that the locomotives can move at high speed when the locomotives are overloading, getting the power in three-phase from the public power network of the power supply system of the traction load of the railway, and eliminating the effect of the traction load of the railway to the power quality of the public power network can be eliminate, which can also be made by the prior traction transformer with low cost and convenient implementation.

This invention relates to an antenna working at the microwave band including a medium substrate, one side of which is adhered with a metal layer as the ground, the other side is adhered with a concave metal plate as a plate stick antenna unit and a micro-strip line as the feeding line connecting to the concave of the metal plate, and an artificial magnetic medium material is set symmetrically at both sides of the micro-strip line and adhered on the substrate. This invention can realize forbidden band at a certain working frequency sphere so as to suppress high order harmonics.

The invention relates to a navigation mark power circuit with topology structure, stable power, and high application. The invention is characterized in that the power supply of function circuit uses LDO as controllable method, using high-efficiency DC-DC-a, DC-DC-b modules and two high-efficiency LDO-a, LDO-b, assisted with a GPRS / GSM communication module and a GPS module, via relative control circuits to form a navigation mark power circuit with high power stability and high application. The invention can insulate the effect of external power supply on the system power, with high power conversion, which can be used in accumulator power supply with various voltages. The invention can improve the interference resistance of terminal, restrain high-order harmonic wave generated in the DC-DC circuits, provide stable power to following circuit and confirm the accuracy of analogue-digit conversion, and support various working modes and low-power-consumption of terminal.

The invention provides a permanent magnet synchronous machine (PMSM) possessing an assembled magnetic effect. The PMSM comprises a stator and a rotor. Air gaps exist between the stator and the rotor. The stator includes a stator core and a stator winding. The rotor includes a rotor core, a rotating shaft and permanent magnet steel. The stator winding is a centralized winding. The rotor is an eccentric rotor. Ends of the permanent magnet steel are directly connected with each other. The air gaps between the stator and the rotor are non-uniform air gaps. The invention has the following positive effects that: (1) distribution of air-gap flux density can be optimized through improving a rotor structure and the air gap flux can be very close to a sinusoidal waveform by using the non-uniform air gaps; (2) magnetic flux leakage on the ends can be effectively reduced because the ends of the permanent magnet steel are directly connected with each other, and simultaneously a magnetic isolation bushing is not needed to be installed on a rotating shaft side so that a requirement of a rotating shaft material can be reduced, wherein the rotating shaft can adopt a magnetic conductive material and / or a non magnetic conductive material.

The invention discloses an alternating current-direct current electric locomotive traction device and a system, wherein the alternating current-direct current electric locomotive traction device comprises a pulse-width modulation (PWM) converter unit and a step-down chopping unit, an input end of the PWM converter unit is connected into a power grid, an output end of the PWM converter unit is connected with a traction motor through the step-down chopping unit, the PWM converter unit converts an alternating current power supply which is connected into the power grid and stabilizes voltage to output direct current, and the step-down chopping unit reduces voltage and chops direct current which is output from the PWM converter unit to be required direct current by controlling switching of a chopping switch pipe, and supplies the required direct current for the traction motor. The system comprises more than one traction converter, wherein each traction converter is provided with a traction controller and more then two sets of traction devices which are respectively connected with the traction controller, and each set of traction device is corresponding to the traction motor. The alternating current-direct current electric locomotive traction device and the system can achieve traction power supply with simple structure, low making cost, steady output of traction energy and high power factor on the basis of that locomotive circuit structures do not need to change.

A circuit achieving power flow control and small current ground fault active compensation arc suppression simultaneously is characterized by comprising a three-phase parallel module, a first coupling transformer, a three-phase serial module, a second coupling transformer and a direct current bus voltage stabilizing unit; when power flow control is conducted, the three-phase parallel module and the first coupling transformer are used for providing active power balance for the interior of the circuit and conducting reactive compensation on the circuit through the first coupling transformer, and when active compensation arc suppression is conducted, the three-phase parallel module and the first coupling transformer are used for providing a zero-sequence compensation current for a small current ground fault; when power flow control is conducted, voltage is inserted into a power distribution system circuit through the second coupling transformer to change power flow; the direct current bus voltage stabilizing unit connects the three-phase serial module with the three-phase parallel module and is used for providing stable direct current voltage for the direct current side of the three-phase serial module and the direct current side of the three-phase parallel module. According to the circuit achieving power flow control and small current ground fault active compensation arc suppression simultaneously, by means of the three-phase parallel module, the three-phase serial module and the direct current bus voltage stabilizing unit, the functions of power flow control small current ground fault active compensation can be achieved simultaneously.

A small broadband vertical polarized all-round antenna includes four antenna units, a central feeding port, a base and four connecting cables, the antenna units are vertical to the base, the positive face is towards the outside arrayed in a 'mouth' shape and distributed symmetrically to the center, in which, the maximum diameter direction of each unit is parallel to the base, the four units are parallel to the central feeding port by four 0.25 wavelength cables to make all vertical polarized equivalent magnetic flow to distribute in a same phase on the antenna with the same structure. Each unit is made up of a ladder-type conductor with a medium plate radiating both sides of the slot positively, a feeding port, a medium plate and two earth units.

The invention discloses a microstrip fed harmonic suppression broadband patch antenna with a compact structure. The broadband patch antenna comprises a single-layer microwave dielectric substrate, a rectangular radiation patch with a working frequency of f1, two quarter-wavelength resonators with a working frequency of f2, two quarter-wavelength resonators with a working frequency of f3, two short-circuit pins with a radius of r and a feeding microstrip line, wherein the rectangular radiation patch with the working frequency of f1 is located at the center of the whole structure; the two quarter-wavelength resonators with the working frequency of f2 share one short-circuit pin with the radius of r, are in near-coupling with a radiation edge of the rectangular radiation patch and are connected with the microstrip line to realize a feeding structure; and the two quarter-wavelength resonators with the working frequency of f3 share one short-circuit pin with the radius of r and are in near-coupling with another radiation edge of the rectangular radiation patch. The bandwidth of the patch antenna is effectively increased, high-order harmonic waves can be effectively suppressed, and the broadband patch antenna is compact and simple in structure, low in profile and easy to implement.

The invention discloses a method for optimizing the magnetic suspension permanent magnet planar motor magnetic steel array parameter. An average fundamental wave amplitude is used for setting the expected gas flux density, and a mathematic model of the expected gas flux density is set up; average fundamental wave amplitudes on different levels are used for calculating the expected flux density overall average fundamental wave amplitude in an effective magnetic field space height range, and a gas flux density harmonic model is used for calculating the average relative mean square error of the practical flux density and the expected gas flux density; the magnetic steel parameter is determined based on the principle that the expected flux density overall average fundamental wave amplitude should be as large as possible, and the average relative mean square error of the practical flux density should be as small as possible, an optimizing result can effectively restrain higher harmonics, and especially, second harmonics are restrained greatly.

The invention discloses an acoustic wave ranging method and device, and relates to the technical field of measurement. The problems of poor measurement reliability and wind speed influence, which arecaused by echo loss and channel interference and the problem of ranging error caused by trigger phase shift caused by echo fluctuations in the existing acoustic wave ranging technology are overcome. According to the technology, a transmitting end sends encoded acoustic waves in a detection frame encoding format and starts effective measuring wave counting; a receiving end is in an acoustic wave receiving state after receiving a pilot code; after a frame start delimiter is detected, effective measuring wave counting is started; when a first effective measuring wave is received, a level handshake signal is sent to the transmitting end; after receiving the level handshake signal, the transmitting end sends a frame end delimiter, stops counting, and counts and transmits the number of the effective measuring waves; after receiving the frame end delimiter, the receiving end counts the number of actually received effective measuring waves; and if two numbers are equal, distance is calculatedbased on the relationship between the counted number of the effective measuring waves and the wavelength.

The invention discloses an electrolytic-capacitor-free motor driving system and a current control method and a current control device thereof. The method comprises the following steps: obtaining current actual supply voltage, current rotating speed command and current actual rotating speed in the system, processing the current actual supply voltage, the current rotating speed command and the current actual rotating speed, and obtaining target total power; obtaining current actual capacitor power in the system, calculating the difference value of the target total power and the current actual capacitor power as target inverter output power; obtaining current actual inverter output power in the system, adjusting the current actual inverter output power based on the difference value of the target inverter output power and the current actual inverter output power, and obtaining current q-axis current command; generating a control signal according to the current q-axis current command, and executing current control of the system. By using the method, the purposes of improving the power factor of the electrolytic-capacitor-free motor driving system and inhibiting higher harmonics can be achieved.

The invention discloses a higher harmonic active stabilization device and method for an alternating current / direct current hybrid microgrid. A core is the higher harmonic active stabilization device with a switching frequency of 100kHz, which is used for compensating higher harmonics in the alternating current / direct current hybrid microgrid. The device disclosed by the invention comprises a DC / ACconverter and a DC / DC converter, and is provided with two ports; the output end of the DC / AC converter is connected with an AC bus, and outputs a damping current for restraining the higher harmonicson the AC side; the output end of the DC / DC converter is connected with a DC bus, and outputs a compensation current for compensating higher ripples on the DC side; and a coordination control method based on current feedforward compensation is adopted, so that the voltage fluctuation of an energy storage capacitor is restrained, and the capacity and the size of the capacitor are greatly reduced. According to the higher harmonic active stabilization device and method for the AC / DC hybrid microgrid, an AC / DC hybrid microgrid system can be more stable.

A power supply system comprising a power supply having a secondary cell and a charging / discharging controller for controlling the charging / discharging of the secondary cell, characterized in that the power supply is connected to a power system of a building in series or parallel, and the power supply or a part of it is installed inside an entrance frame of a landing of an elevator. Since the power supply or a part of it is installed inside an entrance frame of a landing of an elevator, effective use of the building is achieved. Further, since the power supply or a part of it is installed inside the entrance frame of the elevator landing, the maintenance work is facilitated. The lead-in cable of the power supply installed inside of the elevator landing is only the power supply line and the signal line of a power sensor, thereby facilitating the installation work.